Todd Haynes’ films are about shape-shifters, people whose identities are in flux, frequently concealed, even from themselves. You could say that this is the essence of the Jewish experience in the diaspora, and Haynes, whose mother is Jewish, would undoubtedly agree. At any rate, it is the perfect description of the man at the center of Haynes’ new film, “I’m Not There,” which opens on Nov. 21.